A conventional chair with a pivotable seat is shown in FIG. 1 and generally includes a base 80 which includes a horizontal top board 81 and a plurality of flexible pillows 70 connected to the top board 81. A seat 90 includes a top surface 91 and a bottom surface 92, the pillows 70 are connected between the top board 81 and the bottom surface 92 of the seat 90. The two ends of the seat 90 can be pivoted up and down by deforming the pillows 70. Although the conventional chair shown in FIG. 1 provides a pivotable seat which allows the user to change the pose when sitting in the chair, the seat 90 cannot move so that the user has to move his or her body to find out a comfortable pose.
The present invention intends to provide a chair which has a movable seat so that the user can change different poses while the seat is moved with the user's body movement.